The forced resignation of New York Stock Exchange Chairman Dick Grasso could usher in a new age for the world's largest stock market.

Wednesday, Mr. Grasso, 57 years old, was pressured to step down after a public outcry over a $139.5 million retirement-pay package that he had built up over 36 years at the NYSE. Late Wednesday night, the exchange's directors were discussing candidates for the job of interim successor in a conference...